JP2001027678A - Sensor for detecting liquid body and manufacture of frp structural body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality and efficient manufacturing method of an FRP structural material wherein a liquid body impregnated in a fiber reinforced base can be detected when reaching a predetermined position by surely and simply detecting the liquid body and generation of impregnation failures can be prevented. SOLUTION: The sensor for detecting a liquid body comprises a first optical fiber having a light emitting end 4 set to a leading end or to the vicinity of the leading end, and a second optical fiber having an incidence face 5 for receiving the light emitted from the first optical fiber set to a leading end or to the vicinity of the leading end. An FRP structural material is manufactured with the use of the detection method, and the FRP structural material is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a liquid material, and more particularly, to a method particularly effective for detecting a state of impregnation of a liquid material when a reinforcing fiber base material is impregnated with the liquid material.

[0002]

2. Description of the Related Art When an FRP (fiber reinforced plastic) structure is manufactured by impregnating a liquid material into a reinforcing fiber base material shaped by a mold or a core material, the liquid material flows to a predetermined position. Confirm that you have reached the FRP
It is very important in the quality of the structure and in the manufacturing process.

[0003] The flow state of this liquid material can be visually checked from the outside when the mold is transparent, but cannot be confirmed visually when the mold is metal or opaque. Although the flow state of the liquid has been estimated, there is a need for a method of detecting that the liquid has reached a predetermined position without fail.

As a method for detecting the presence or absence of this liquid material,
An optical fiber is sandwiched between a bending mold for giving a bend to an optical fiber and a swelling material that swells due to the infiltration of the liquid material, and is housed in a case. As a result, since the optical fiber is deformed along the pressing die, there is known a method of detecting the presence of a liquid by changing the amount of light transmitted through the optical fiber. However, this method requires a jig for fixing the optical fiber and the swelling material, and this jig may hinder the flow of the liquid material. Further, since the swelling material needs to swell with the liquid to be detected, there is a problem that it is necessary to select a swelling material suitable for the liquid.

As another method for detecting a liquid material, a liquid contact material layer is provided on the outer periphery of an optical fiber, and the liquid contact layer contracts or swells when the liquid material comes into contact with the liquid material, thereby causing optical transmission loss and optical transmission loss of the optical fiber. A method of detecting the presence of a liquid material from a change in backscattered light is known (Japanese Patent Application Laid-Open No. H10-735).
09 publication). However, in this method, since the liquid contact responsive layer needs to be wound around the outer periphery of the optical fiber, it is necessary to select a liquid contact responsive layer that contracts or swells with the liquid material to be detected, as described above.

As described above, the prior art requires a fixing jig for an optical fiber and a swelling material, and this jig impedes the flow of the liquid material and requires selection of a swelling material suitable for the liquid material. There are problems.

Further, the liquid material is detected because the optical transmission loss and the backscattered light are changed by bending or compressing the optical fiber. However, the change in the optical transmission loss and the backscattered light is very small. Therefore, it is necessary to detect a change in the amount of light with high accuracy, and there is a problem that the apparatus becomes expensive.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for detecting a liquid material, which solves the above-mentioned conventional problems and provides a simple and reliable method for detecting a liquid material.

Further, the present invention provides a method for reliably detecting a liquid material, thereby detecting that the liquid material impregnated in the reinforcing fiber base has reached a predetermined position, and stabilizing the production of the FRP structure. It is another object of the present invention to provide a method of manufacturing an FRP structure to achieve an improvement in production yield and quality.

[0010]

The liquid material detection sensor according to the present invention has the following structure to solve the above-mentioned problems.
That is, a first optical fiber having an emission surface for emitting light at the tip or near the tip, and a first optical fiber having an incidence surface for receiving light emitted from the first optical fiber at the tip or near the tip. It is characterized by comprising two optical fibers.

The liquid material refers to a resin, a liquid, a gel (jelly), a slurry, and the like. Also, as the resin,
Thermosetting resins such as epoxy, unsaturated polyester, phenol and vinyl ester; thermoplastic resins such as nylon and ABS resin; and a mixture of a thermosetting resin and a thermoplastic resin.

Further, the first optical fiber and the second optical fiber are adjacent to each other, and each of the exit surface of the first optical fiber and the incident surface of the second optical fiber It is characterized in that the presence or absence of the liquid is determined by having a configuration in which the surfaces are inclined and the inclined surfaces face each other.

That is, this is a method for detecting a liquid using an optical fiber, wherein two optical fibers are arranged in parallel.
As this optical fiber, a cocoon-shaped twin-core product obtained by fusing the covering portion is commercially available and may be used. Alternatively, two single-core optical fibers may be adhered to each other using an adhesive to be adjacent to each other. In addition, a single-core optical fiber may be laid in parallel without bonding, but a mechanism that does not rotate the fiber tip is required.

By detecting the presence or absence of a liquid material from the change of the emitted light or the scattered light at the tips of the two adjacent optical fibers, a jig for fixing the optical fiber and the swelling material is not required. It does not obstruct the flow of the liquid.

Further, since no swelling material or liquid contact material is used, there is no need to select a swelling material or liquid contact material suitable for the liquid material. Therefore, simple and reliable detection of the liquid material becomes possible.

Further, a method of manufacturing an FRP structure according to the present invention has the following configuration in order to solve the above problems. That is, the FRP structure is characterized in that the detection of the resin impregnated in the reinforcing fiber base material is performed using a liquid detection sensor, the impregnation state of the resin is determined based on the detection result, and the impregnation step is controlled. It is a method of manufacturing the body.

Here, an example of a method of manufacturing an FRP structure according to the present invention will be described below. [1] A reinforcing fiber base made of glass fiber or carbon fiber is arranged on one or both sides of a core material made of a foam, the whole is covered with a cover film, and the inside covered with the cover film is evacuated. [2] FRP liquid material is injected from an injection port separately provided when the cover is covered with the cover film, and is diffused on the surface of the reinforcing fiber base material.
An RP structure can be obtained.

According to the present invention, when the above-described FRP structure is manufactured, the optical fiber may be formed between the core and the reinforcing fiber base, between the reinforcing fiber base and the cover film, between the reinforcing fiber base layers, and the like. By laying at a position where the impregnation state of the liquid material is to be detected, it is possible to easily determine that the liquid material, particularly the resin, has been impregnated at a predetermined position in the impregnation step. Is effective as

As the resin, a thermosetting resin such as epoxy, unsaturated polyester, phenol, and vinyl ester is preferably used in terms of moldability and cost. However, a thermoplastic resin such as nylon or ABS resin, or a mixed resin of a thermosetting resin and a thermoplastic resin can also be used. In addition, in order to improve the quality of the FRP structure, a pigment may be mixed with the resin by several% to color the FRP structure material. As the pigment, a mixture of an inorganic toner and a resin is used. As an example of the white pigment, titanium oxide: 49%,
It can be obtained by mixing silicon oxide: 2% and unsaturated polyester resin 49% (all by weight).

[0020]

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

First, the first embodiment will be described. FIG.
, Two optical fibers are used, and one is
Outgoing optical fiber 2 having
The outgoing surface 4 and the incident surface 5 are configured as the incident optical fiber 3 having The light source light 13 emitted from the light source 11 is condensed by the condensing lens 12 as necessary, and then enters the outgoing optical fiber 2. This light is guided by the output optical fiber 2 and is output from the output surface 4. Here, a part of the light emitted and scattered from the emission surface 4 is made incident on the incidence surface 5 of the incident optical fiber 3, guided by the incident optical fiber 3, and becomes detection light 16 at the other end, and is a light receiving element. 18 and are detected.

Next, the exit surface 4 and the entrance surface 5 in the above configuration will be described. As shown in FIG. 3, the outgoing face 4 or the incoming face 5 of the optical fiber is cut obliquely, and the cut faces face each other. Cutting angle φ of this cut surface
1 and φ2 are desirably cut at 10 to 70 degrees.

As shown in Table 1, when the cutting angle is increased, the facing area of the optical fiber is reduced, so that the outgoing light 14, the incident light 15 and the detection light 16 are reduced, and the detection by the light receiving element 18 becomes difficult. . On the other hand, when the cutting angle is reduced, the outgoing light 14, the incident light 15 and the detection light 16 increase because the facing area of the optical fiber increases, and the detection by the light receiving element 18 becomes easy, but the cutting of the optical fiber becomes difficult. Therefore, it is more desirable to cut at an angle of 30 to 60 degrees.

The measurements shown in Table 1 were performed in the following manner.
As a detector, a light emitting diode is provided in a light source for emission,
Using a keyence optical fiber sensor (model: FS-V1) capable of converting the detection light into a digital value and displaying,
The detection light obtained by the optical fiber for incidence was read as a digital value. The amount of light indicated by this digital value is approximately 0.14 nW per digital display.

The optical fiber used is a twin-core plastic optical fiber formed by fusing the coated portion and forming into a cocoon shape, having an outer diameter of 2.3 mm and an outer diameter of the core of 1 mm. The tip was cut to a length of 1 m, and the tip was cut at an angle of about 20 to 90 degrees. The detection light in the air was summarized in Table 1. The cocoon-shaped optical fiber refers to an optical fiber having a cross section cut along a broken line AB shown in FIG. 1 having a shape shown in FIG. The core material of the optical fiber core 6 is PMMA (polymethyl methacrylate), the cladding material is a fluorine-containing polymer, and the optical fiber coating 7 is PE (polyethylene). This is a plastic optical fiber having a configuration to cover.

In this case, the outer diameter of the optical fiber cable is 1
mm, and an optical fiber coated outer diameter of 2.3 mm was used. The smaller the outer diameter of the coating of the optical fiber, the less the flow of the liquid material is hindered. However, if the outer diameter of the coating is too small, the amount of light returning to the incident side decreases, so that stable detection becomes impossible. Therefore, it is preferable that the coating outer diameter of the optical fiber is 0.5 mm or more and 3 mm or less, and the optical fiber core wire outer diameter is 0.1 mm or more and 2 mm or less.

It is difficult to measure the cutting angles φ1 and φ2 due to the lack of the end of the cut surface. If the cut surface has a curved surface or a multi-sided shape, the normal line or the area of each surface is required. The angle can be defined by the average value of each normal weighted by the magnitude of.

Further, the cut surface of the optical fiber does not necessarily have to be sharp, and may be a trapezoidal shape with the tip cut off.

As another shape of the cut surface, FIG.
As shown in FIG. 7, the facing surfaces in an arc shape may be concave or convex.

As another method for obtaining a cut surface, as shown in FIG. 7, a configuration may be adopted in which a hole is made in the center of an optical fiber arranged in parallel. The position of this hole is not particularly limited, but it is desirable to open the hole several mm to several cm from the tip of the optical fiber in order to save the optical fiber.

Next, the principle of detecting the liquid material on the cut surface will be described below. As shown in FIG. 3, the light propagating through the output optical fiber 2 is incident on the output surface 4 cut at an angle φ1 at an incident angle θ1, and is output from the output surface 4 at an angle θ2 to become output light 14. . At this time, the refractive index of air is n
2. Assuming that the refractive index of the optical fiber is n1, since n1> n2, θ2> θ1 according to Snell's law. Therefore, in the above state, the outgoing light 14 emitted from the emission surface 4 cannot enter the incidence surface 5.
However, the exit surface 4 and the entrance surface 5 in the cut surface have fine irregularities on the surface. As an example, an uneven portion is enlarged and shown by a wavy circle C in FIG.

As shown here, the outgoing light 14 emitted from the outgoing surface 4 at an angle of θ 2 is reflected by the convex portion 20 to become the incident light 15 and enters the incident surface 5. This light is guided by the incident optical fiber 3 and can be detected by the light receiving element.

When a liquid material (for example, a mixture of a vinyl ester resin and a pigment) that blocks light adheres to the cut surface, the emitted light 14 or the incident light 15 is blocked, so that the detection light is smaller than in the air. Decrease.

On the other hand, a case where water or a transparent liquid material adheres to the cut surface will be described with reference to FIG. When water having a refractive index of 1.33 or a transparent liquid 1 having a refractive index of 1.4 to 1.6 (for example, vinyl ester resin) adheres to the cut surface, the refractive index of the optical fiber becomes 1.4 to 1.. This means that the cut surface has been covered with a liquid having a refractive index substantially equal to that of No. 5, and the fine irregularities on the exit surface 4 and the entrance surface 5 disappear, as shown by the dashed line in FIG. Therefore, the emission angle θ
2 is emitted at almost the same angle as the incident angle θ1, so that the incident light 15 shown in FIG. 4 hardly occurs. For this reason, the detection light 16 propagated to the light receiving element 18 is reduced, and it is possible to detect water and a transparent liquid.

The present invention can be used not only for detecting the impregnation state in the impregnation step of the liquid material of the FRP structure, but also for confirming the filling state of concrete, for example.

Next, the second embodiment will be described. As shown in FIG. 8, the light source light 13 emitted from the light source 11 is condensed by the condensing lens 12 as necessary, and then enters the emission optical fiber 2. This light is guided by the output optical fiber 2 and is output from the output surface 4. The outgoing light 14 emitted from the outgoing surface 4 is reflected by the inner surface of the cap 21 having the flow hole 22 attached to the tip of the optical fiber, and the reflected light 1
7 and enters the incident surface 5. This light is guided by the output optical fiber 3 and is used as the detection light 16 as a light receiving element 18.
Is detected by

In the above configuration, when the liquid 1 flows through the flow hole 22 of the cap 21, the outgoing light 14 or the reflected light 17 is blocked, so that light does not enter the incident surface 5. For this reason, the detection light 16 is reduced, and the liquid material can be detected.

As described above, in the first embodiment, the optical fiber and the fixing jig for the swelling material are not used, and only the twin optical fibers are used.
Almost no obstruction of liquid flow.

In the method using the cap shown in the second embodiment, the outer diameter of the jig can be made almost the same as the outer diameter of the optical fiber.
When installed in the flow path of the liquid, it hardly obstructs the flow of the liquid.

In both the first and second embodiments, since the reflecting tip jig is provided on the optical fiber alone or on the tip of the optical fiber, a swelling material or a liquid contacting material suitable for the liquid material shown in the prior art is used. There is no need to select However, when the optical fiber is affected by the liquid material, it may be difficult to use the present invention.

Although the incandescent lamp or the laser may be used as the light source 11 for emission as described in the first and second embodiments, it is preferable to use an inexpensive, small-sized and long-life light emitting diode. . The light receiving element 1 for detecting the detection light 16
Although a photoelectric tube or a photomultiplier tube may be used for 8, it is desirable to use an inexpensive, small-sized and long-life photodiode. A glass optical fiber may be used for the optical fiber. Particularly, the core material is made of polymethyl methacrylate (PMMA), styrene, polycarbonate, and the cladding material is made of fluorine containing fluorine whose refractive index is lowered by adding fluorine. It is preferable to use a plastic optical fiber using the union. Above all, it is more preferable to use a plastic optical fiber using PMMA as a core material because the transmittance is high, the processing is easy, and the cost is low.

In this case, the outer diameter of the optical fiber cable is 1
mm, and an optical fiber coated outer diameter of 2.3 mm was used. The smaller the outer diameter of the coating of the optical fiber, the less the flow of the liquid material is hindered. However, if the outer diameter of the coating is too small, the amount of light returning to the incident side decreases, so that stable detection becomes impossible. Therefore, it is preferable that the coating outer diameter of the optical fiber is 0.5 mm or more and 3 mm or less, and the optical fiber core wire outer diameter is 0.1 mm or more and 2 mm or less.

Further, each of the optical fibers may be independent and two single-core optical fibers may be used, but it is preferable to use a twin-core optical fiber in which two optical fibers are manufactured in a cocoon shape.

Since the material of the cap needs to reflect light on the inner surface, metal or white plastic is preferable. In addition to the cylindrical shape, a configuration in which a strip-shaped flat plate having the same width as the optical fiber is bent into a U-shape and attached to the tip of the optical fiber may be employed.

[0045]

Next, an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

Example 1 As shown in FIG. 1, a double-core plastic optical fiber formed by fusing the covering portion and forming a cocoon shape was cut out to a length of 1 m, and the cutting angle at the tip was set to about 3 mm.
Cut at an angle of 0 degrees. The cocoon-shaped optical fiber has the shape shown in FIG. 2 and is a cross-sectional view taken along the broken line AB shown in FIG. The core of the optical fiber core 6 shown here is made of PMMA, the cladding material is made of a fluorine-containing polymer, the optical fiber coating 7 is made of PE, and the plastic covering the entire circumference of the optical fiber core 6. Optical fiber. Also, here, the outer diameter of the optical fiber core is 1
mm, and an optical fiber coated outer diameter of 2.3 mm was used.

Next, as a detector, an optical fiber sensor (model: FS-V) manufactured by Keyence and equipped with a light emitting diode as a light source for emission and capable of converting and displaying incident light into digital values.
Using 1), the detection light obtained by the incident optical fiber was read as a digital value. The amount of light indicated by this digital value is approximately 0.14 nW per digital display.

Table 2 shows how the detection light changes in each measurement object.

As described above, the vinyl ester resins shown in the table are general FRP resins used when manufacturing an FRP structure.

The pigment is an opaque colorant mixed with the vinyl ester resin in order to improve the quality of the manufactured FRP structure. Titanium oxide and silicon oxide, which are inorganic toners, are converted into unsaturated polyester resin. It is a mixture. In this example, 3% of the pigment was mixed in with respect to the weight of the vinyl ester resin.

As can be seen from the results shown in Table 2, when the optical fiber sensor detection light between air and vinyl ester resin or vinyl ester resin + pigment is compared, there is a clear difference between air and each resin. It can be seen that detection is possible.

[Embodiment 2] As shown in FIG.
Similarly, a plastic optical fiber 1 having a length of 1 m
And the end of the optical fiber was cut along a plane perpendicular to the axis. A cylindrical cap made of aluminum was attached to the tip of the optical fiber. The diameter of the inflow hole formed in the cylindrical cap was approximately 2 mm. The optical fiber used here was of the same type as that of the first embodiment. Also,
The detector used the same optical fiber sensor as in Example 1 to read the detection light obtained from the incident optical fiber as a digital value.

It was examined how the detection light changes in each measurement object. Table 3 shows the results.

As can be seen from the results shown in Table 3, when the light detected by the optical fiber sensor in the air and vinyl ester resin or vinyl ester resin + pigment is compared, there is a large difference in the detected light between air and each resin. It can be seen that the detection of is possible. In particular, the vinyl ester resin + pigment has a large difference as compared with the detection light in the air, indicating that the detection is easier.

[0055]

[Table 1]

[0056]

[Table 2]

[0057]

[Table 3]

[0058]

According to the present invention, detection of a liquid material can be performed simply and reliably.

Further, since the liquid material can be reliably detected,
Since it is possible to detect that the liquid material impregnated in the reinforcing fiber base has reached a predetermined position, the production of the FRP structure is stabilized, and the production yield and the quality can be improved.

[Brief description of the drawings]

FIG. 1 is an example of a schematic view of a method for detecting a liquid material according to the present invention.

FIG. 2 is an example of a cross-sectional shape of an optical fiber formed into a cocoon shape according to the present invention.

FIG. 3 is an example of light emission from an optical fiber cut surface according to the present invention.

FIG. 4 is an example of light emission from an optical fiber cut surface according to the present invention.

FIG. 5 is an example of light emission when water or a transparent liquid material adheres to a cut surface of an optical fiber according to the present invention.

FIG. 6 is an example of a shape of an optical fiber cut surface according to the present invention.

FIG. 7 is an example of a shape of an optical fiber cut surface according to the present invention.

FIG. 8 is an example of a schematic view of a liquid material detection method according to the present invention.

[Explanation of symbols]

 1: liquid material 2: outgoing optical fiber 3: incoming optical fiber 4: outgoing surface 5: incoming surface 6: optical fiber core wire 7: optical fiber coating 11: light source 12: condensing lens 13: light source light 14: Outgoing light 15: Incident light 16: Detection light 17: Reflected light 18: Light receiving element 20: Convex portion 21: Cylindrical cap 22: Flow hole δ1: Reflection angle inside optical fiber θ1: Light incident angle on emission surface 4 θ2: the light emission angle at the light exit surface 5 n1: the refractive index of the optical fiber n2: the refractive index of air C: the enlargement of fine irregularities on the light exit surface 4 φ1, φ2: the cut angle of the optical fiber

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 2G065 AA04 AB09 AB23 AB24 AB27 AB28 BA09 BA17 BA18 BB02 BB22 BC28 DA15 DA20 2H038 AA09 4F205 AA36 AA41 AD02 AD05 AD16 AD17 AM14 AM28 AP06 AP20 AQ01 AR20 HA06 HA42 HC16 HC17 HF30 HF01 HF01 HF01 HF01 HK19 HM06

Claims (7)

[Claims] 1. A first optical fiber having an exit surface for emitting light at or near a tip, and an incident surface for receiving light emitted from the first optical fiber is located at or near a tip. 2. A liquid material detection sensor comprising a second optical fiber according to claim 1. 2. The optical fiber according to claim 1, wherein said first optical fiber and said second optical fiber are adjacent to each other, and each of said exit surface of said first optical fiber and said entrance surface of said second optical fiber is provided. The liquid material detection sensor according to claim 1, wherein the surfaces are inclined, and the inclined surfaces face each other. 3. The liquid material detection sensor according to claim 1, wherein a member that reflects light is disposed at a position facing the first optical fiber and the second optical fiber. 4. A cap having one end closed and an inner surface made of a material reflecting light, the other end being open, and a cap having a flow hole through which a liquid material flows in a part of a peripheral surface. 2. The liquid material detection sensor according to claim 1, wherein the respective distal ends of the first optical fiber and the second optical fiber are inserted into the cap from an end. 3. 5. The liquid material detection sensor according to claim 1, wherein the liquid material is a resin. 6. A method for detecting a resin impregnated in a reinforcing fiber base using the liquid material detection sensor according to claim 5, determining a resin impregnation state based on the detection result, and performing an impregnation step. A method for producing an FRP structure, comprising controlling. 7. An FRP structure comprising a liquid material detection sensor according to claim 1.